This study was performed in 2003–05 to determine the serological status of a sample of pregnant women as a preliminary study for the rubella vaccination programme. Out of 965 pregnant women attending health centres affiliated to Tehran University of Medical Sciences for prenatal care, the estimated rubella immunity rate was 91.1% (95% CI 89.3%–92.9%) and the nonimmunity rate was 8.9% (95% CI 7.1%–10.7%). The rubella immunity rate differed in different areas of Tehran but not significantly so. However, there was a significant difference in the level of rubella immunity by the number of persons per household and by age, but no significant relationship with economic status, occupation or level of education.